1. Field of the Invention
This invention relates to a reversible light-sensitive glass, e.g., for eyeglasses, which contains the colored rare earth elements of Nd.sub.2 O.sub.3 Ho.sub.2 O.sub.3 and Er.sub.2 O.sub.3 having an anti-dazzling effect and which has a refractive index of 1.50 to 1.55, and in which the percent transmission of the glass changes abruptly and reversibly due to irradiation with ultraviolet light and visible light of short wavelengths.
2. Description of the Prior Art
Generally, eyeglasses are roughly classified into those glasses intended to correct faulty vision and sunglasses for protecting the eyes from the strong glare of the sun. The present invention provides a reversible light-sensitive glass for eyeglasses having both of these properties and in which the percent transmission changes with the intensity of the light.
The glasses used for eyeglasses having the above two properties, include those glasses obtained by incorporating or coating a small amount of a coloring component into or on a conventional colorless glass for eyeglasses and reversible light-sensitive glasses for eyeglasses. The former scarcely have any anti-dazzling effect under the strong glare of the sun. The latter also have poor anti-dazzling effects when looking at bright outdoor views from inside a dark room, since the glasses do not become colored unless they are directly exposed to light.